Philippa Stevenson: You don't have to be bats to live in Hamilton

Inevitably, Andrea Dekrout is known as Batgirl.

Last year, the Hamilton PhD student was the first to confirm what had been long suspected about the city: it has bats.

Also inevitably, some will want to play with the bad puns. Personally, it's been a battle of heroic proportions not to go all Batman and Robin, sprinkle belfries left, right and centre and wonder whether Penguin, the Joker and Catwoman might emerge in Gothamilton as well.

It makes a nice change from the cow gags.

And now to the Batcave for some serious batbusiness. (Oops, sorry, one got away.)

I was pretty chuffed to learn that Hamilton is home to one of New Zealand's rarest species and its only native land mammal. And very surprised.

Dekrout, who is an Auckland University student because it is a centre of bat research, but who works in a small corner of Waikato University, said most Hamiltonians were surprised to find they share their city with the elusive, threatened animal, known in Maori as pekapeka and associated with the mythical, night-flying bird, hokioi, which foretells death or disaster.

It's true, said Dekrout, bats don't get good press but at least she's happier with the Batgirl nickname than the one prompted by her last study subject - hedgehogs.

Most people mistake the tiny, insect-eating, long-tailed bats that weigh around 10gm and have a wingspan of just 20cm for moths. They can fly at 60km/h, using echo-location calls to navigate, so at best, too, they are only a moth-like blur.

The challenge for 25 volunteers Dekrout has organised to search the city kilometre by kilometre tomorrow and Saturday night is to locate that blur on the wing or spy out its roosts.

Working in pairs and using hand-held ultrasound radios that detect and make the bats' calls audible to human ears, Dekrout's "bat blitz" is designed to get some idea of how many of the chestnut-brown bats are in the city, and their movements.

She already knows they tend to use the Waikato River as a highway, zipping along it and scooping up insects emerging from the water in a membrane attached to their tail. It's that membrane that distinguishes the more widespread long-tailed bat, Chalinolobus, from its rarer, short-tailed cousin, Mystacina, which has a free tail.

Dekrout's survey is the first of its kind. The bats have been studied in rural areas including Southland and the King Country but never in a city.

When it's complete she plans to catch about 30 bats to which she'll glue a radio transmitter "the size of your pinky fingernail" and weighing less than half a gram.

The miniature transmitters will enable the bats to be located during the day and help pinpoint their roosts, which will be studied to determine what kind of environment the animals like to hang about in, and what threatens them.

With that information Dekrout, whose work has attracted a number of grants, should be able to predict what will help the bats survive. Threats could include predators and declining vegetation. Ultimately, she hopes to design a management plan that will fit with an existing, nationwide Conservation Department bat recovery plan.

Our towns and cities are the only ecosystems that are expanding worldwide. Dekrout hopes her study will allow urban growth to be managed in such a way that people and bats are able to happily live side by side.

It might mean, for instance, Hamilton protecting areas popular with the bats or encouraging property developers to leave certain vegetation favoured by bats in place when new houses are built.

Dekrout describes her work in talks to groups and schools. "I have managed to avoid dressing up as Batgirl," she said, "but I did give a talk to some school kids once and all the little ones dressed in theme, which was very cute."

The project has drawn a good response with plenty willing to be Robin-like sidekicks to her Caped Crusader.

Over the past year, more than 60 volunteers have helped with previous ultrasound surveys and other fieldwork.

"I'm always keen to find out if anyone has spotted bats so that we can get a better idea of their range across the island and/or all of New Zealand," Dekrout said.

Bat spotters can report sightings to her email adek004@ec.auckland.ac.nz (link below).